Vasoactive substances in blood and urine of DCA hypertensive rats.

• H. Croxatto et al. have demonstrated that on incubation for 24 hours at 38 C. and pll 3.8 to 4, the serum of each of the animals they studied (including mammals, birds, and amphibia) produced a peptide which causes smooth muscle contraction. This peptitle: lias been named "auephrotonsin.'' Slight pharmacological differences were found among the anephrotensins obtained from the. several types of animals, but cadi was capable of raising the blood pressure of the nephrectomized animal into which it was injected intravenously.Rat anephrotensiii, injected intravenously, lowered the blood pressure of normal rats; added to the bath solution it caused the contraction of isolated smooth muscle from the ileum of the guinea pig, the caecum rectalis of the chicken, and the uterus of the rat. The last named is the most sensitive of the tissues studied. A further finding from their studies is that serum from nephrectomized animals yields much greater anephrotensiu activity than comparable serum from normal animals. Differences between normal and nephrectomized animals in their response to, and production of, aneplirotensin led us to inquire whether there are similar differences in these respects between normal rats and rats made hypertensive by DCA treatment; and, further, to see whether there are any detectable changes in kidney function which might be associated with differences in the anephrotensin recovered from the serum.